Managing updates and copying data in a point-in-time copy relationship expressed as source logical addresses and target logical addresses

ABSTRACT

Provided are a computer program product, system, and method for managing updates and copying data in a point-in-time copy relationship expressed as source logical addresses and target logical addresses. A copy relationship indicates a source set of a subset of source logical addresses to copy to a target set comprising a subset of target logical addresses. An update is received to a source logical address that has not been copied. Determinations are made of the target logical address corresponding to the source logical address to be updated according to the copy relationship, a target group of target logical addresses in the target set that include the determined target logical address, and the source logical addresses in the source set that correspond to the target logical addresses in the target group. The determined source logical addresses are copied to the target logical addresses in the determined target group.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a computer program product, system, andmethod for managing updates and copying data in a point-in-time copyrelationship expressed as source logical addresses and target logicaladdresses.

2. Description of the Related Art

In a storage environment, volumes may be copied to other volumes toprovide redundant copies of data or to store data as of a point-in-time.Snapshot is a common industry term denoting the ability to create apoint-in-time (PiT) copy of all the data. Typically, snapshot creationis done instantly and the data is copied only when modified, referred toas a copy-on-write, in order to preserve the data as of thepoint-in-time the snapshot was created. Further, a background copyoperation may be specified to copy the source data in the background tothe target site to provide a redundant copy of the source data. Asnapshot or PiT copy may be created using PiT copy techniques, such asIBM FlashCopy® (FlashCopy is a registered trademark of InternationalBusiness Machines, Corp. or “IBM”).

To establish a PiT copy relationship between source data and targetdata, the IBM Data Facility Storage Management Subsystem (DFSMS)available with the IBM z/OS® operating system provides a FlashCopyestablish (FCESTABL) command that allows the user to specify a sourcevolume to copy to a target volume. The user may specify to only copydata in the source volume that is updated or to perform a backgroundcopy of the source volume to the target volume. (z/OS is a registeredtrademark of IBM in the United States and other countries).

The FCESTABL command also allows the user to specify a list of extentsfor the PiT copy, which comprises contiguous tracks that are less thanall of the source volume and the target volume. The extents specified inthe FCESTABL command indicate the first and last tracks on the sourceand target devices, which may be specified in cylinder and head number.

There is a need in the art for improved techniques for establishing aPiT copy relationship and managing a PiT copy relationship after therelationship is established.

SUMMARY

Provided are a computer program product, system, and method for managingupdates and copying data in a point-in-time copy relationship expressedas source logical addresses and target logical addresses. A copyrelationship indicates a source set of a subset of source logicaladdresses in the at least one storage to copy to a target set comprisinga subset of target logical addresses in the at least one storage. Thesource logical addresses map to source tracks and wherein the targetlogical addresses map to target tracks. An update is received to asource logical address within the source set of logical addresses thathas not been copied to the corresponding target logical address as partof the copy relationship. A determination is made of the target logicaladdress corresponding to the source logical address to be updatedaccording to the copy relationship. A determination is made of a targetgroup of target logical addresses in the target set that include thedetermined target logical address, wherein the target logical addressesin the target group are in the target set. A determination is made ofthe source logical addresses in the source set that correspond to thetarget logical addresses in the target group. The determined sourcelogical addresses are copied to the target logical addresses in thedetermined target group.

In further embodiments, a copy operation is initiated to copy sourcelogical addresses in the source set to target logical addresses in thetarget set. Target logical addresses in the target set are selected thathave not been updated in response to initiating the copy operation. Adetermination is made of source logical addresses from the source setthat are to be copied to the selected target logical addresses. Thedetermined source logical addresses are copied to the selected targetlogical addresses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a computing environment.

FIG. 2 illustrates an embodiment of a PiT copy establish command toestablish a PiT copy relationship.

FIG. 3 illustrates an embodiment of source/target relationshipinformation.

FIG. 4 illustrates an embodiment of a copy map for the PiT copyrelationship.

FIGS. 5 a and 5 b illustrate an embodiment of operations to establish aPiT copy relationship.

FIG. 6 illustrates an embodiment of operations to process an update to asource logical address in a PiT copy relationship.

FIG. 7 illustrates an embodiment of operations to perform a backgroundcopy operations for a PiT copy relationship.

DETAILED DESCRIPTION

Described embodiments provide techniques for managing an update andbackground copy operation for a source logical address in a PiT copyrelationship specifying ranges of source and target logical addresses.Described embodiments use the mapping of source logical addresses andtarget logical addresses to determine the source logical addresses tocopy to target tracks when updating a source logical address in the PiTcopy relationship. Described embodiments further provide techniques forcopying source logical addresses to target logical addresses in the PiTcopy relationship during a background copy operation to copy the sourcelogical addresses to specified target tracks having target logicaladdresses in the relationship. The described embodiments allow themanaging of updates and background copy operations for source logicaladdresses in a PiT copy relationship when source and target data areexpressed as logical addresses and when different ranges of source andtarget logical addresses are specified.

FIG. 1 illustrates an embodiment of a computing environment having acontroller 2 to copy data from a coupled source storage 4 a having oneor more logical volumes 6 a to a coupled target storage 4 b having oneor more volumes 6 b. The controller 2 includes a processor 8 and memory10. Hosts (not shown) may direct read and write requests to the firstcontroller 6 a to access tracks in the first storage 4 a and the secondstorage 4 b. A host write to a track in the first storage 4 a in apoint-in-time (“PiT”) copy relationship 16 may result in the replicationof that track to the second storage 4 b. In a further embodiment, thetarget storage 4 b may be coupled to a target controller, so that thecontroller 2 would communicate the PiT data being copied to the targetcontroller to manage the copying to the target storage 4 b. Thecontroller 2 may communicate with the storages 4 a, 4 b over a network10.

The memory 10 includes a copy manager 12 to copy data from the sourcestorage 4 a to the target storage 4 b as specified in one or more PiTcopy relationships 14. A copy relationship 14 may identify sourcelogical addresses in a source volume 6 a to copy to target logicaladdresses in a target volume 6 b. Alternatively, both the source andtarget logical addresses in the PiT copy relationship 14 may be in asame volume in one of the storages 4 a, 4 b. The data to copy in thecopy relationship 14 may be part of a consistency session or consistencygroup, such that data is copied in a manner to maintain consistencyacross all dependent data, so that the order of dependent writes ispreserved to make the data consistent as of a point-in-time.

The PiT copy relationship 14 includes source relationship information 20and target relationship information 22 both providing information on thesource and target tracks involved in the copy operation. Thisinformation is used to manage I/O requests to the source and targetvolumes to determine if the I/O requests are to tracks involved in a PiTcopy operation. The PiT copy relationship 14 further includes a copy map24 indicating tracks in the target volume 6 b to which source logicaladdresses in the source set need to be copied.

The copy manager 12 may implement a PiT program such as IBM FlashCopy®,snapshot, and other PiT programs, to perform a PiT copy operationbetween specified source and target logical addresses in the same ordifferent volumes. or volume. (FlashCopy is a registered trademark ofInternational Business Machines, Corp. or “IBM”). The PiT copy operationmay be between a source set of source logical addresses comprising asubset of the logical addresses in a source volume 6 a and a target setof target logical addresses comprising a subset of the logical addressesin a target volume 6 b. The logical addresses may comprise logical blockaddresses (LBAs) that map to contiguous tracks in the volumes 6 a, 6 b.

The copy manager 12 is shown in FIG. 1 as program code loaded into thememory 10 and executed by the processor 8. Alternatively, some or all ofthe functions of the copy manager 12 may be implemented in hardwaredevices in the controllers 6 a, 6 b, such as in Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGA), etc.The controller 2 may include other programs not shown, such as anoperating system and application programs.

The memory 10 may comprise one or more volatile or non-volatile storagedevices, such as a Dynamic Random Access Memory (DRAM), Random AccessMemory (RAM) or a non-volatile memory, e.g., battery backed-up RandomAccess Memory (RAM), static RAM (SRAM), solid state storage devices(SSDs), etc.

The storages 4 a, 4 b may each comprise one or more storage devicesknown in the art, such as interconnected storage devices, where thestorage devices may comprise hard disk drives, solid state storagedevice (SSD) comprised of solid state electronics, such as a EEPROM(Electrically Erasable Programmable Read-Only Memory), flash memory,flash disk, Random Access Memory (RAM) drive, storage-class memory(SCM), etc., magnetic storage disk, optical disk, tape, etc. Thestorages 4 a and 4 b may store tracks in a Redundant Array ofIndependent Disks (RAID) configuration where strides of tracks arewritten across multiple storage devices comprising the storages 4 a, 4b. ranks.

The network 10 may comprise a network such as a Local Area Network(LAN), Storage Area Network (SAN), Wide Area Network (WAN), peer-to-peernetwork, wireless network, etc.

FIG. 2 illustrates an embodiment of a PiT copy establish command 50 thatis submitted within the controller 2 or from an attached host to causethe copy manager 12 to generate a PiT copy relationship 14. The PiT copyestablish command 50 includes a command field 52 specifying the PiT copyestablish command; a first source logical address 54 to be copied; alast source logical address 56 to be copied; a first target logicaladdress 58 to which the first source logical address 54 is copied; and alast target logical 60 to which the last source logical address 56 iscopied; and other parameters 62, such as a background copy parameterindicating whether a background operation is performed to copy thesource logical address to the target logical addresses and indicatingwhether the source logical addresses should remain persistent afterbeing copied. The command 50 further would indicate the source volume 6a including the source logical addresses and the target volume 6 bincluding the target logical addresses in the PiT copy relationship 14being established. Additional information may further be indicated, suchas the source 6 a and target 6 b volumes or single volume 6 a, 6 b inwhich the copy operation is being performed. The source and targetlogical addresses may be stored in data storage devices other thanlogical volumes. From the range of first 54 and last 56 source logicaladdresses, the number of logical addresses to copy may be determined.

When processing the PiT copy establish command 50, the copy manager 14generates data structures and information for the PiT copy relationship14 as shown in FIGS. 3 and 4.

FIG. 3 shows fields 70 included in the source 20 and target 22relationship information, which includes a PiT copy identifier (ID) 72identifying the PiT copy for the information; a first source logicaladdress 74 including the first source logical address 54 to copy; afirst target logical address 76 to which the first source logicaladdress 74 is copied; a length related to a number of the logicaladdresses to copy 78, such as in the field 58; and the other parameters80, such as included in the field 60. The number of logical addresses tocopy 78 may alternatively be expressed in other storage units, such asthe number of target tracks or extents to copy. The source and targetrelationship information 70 would further indicate the source volume 6 aincluding the source logical addresses and the target volume 6 bincluding the target logical addresses in the relationship 14. Thesource and target relationship information 70 may be used to manageaccess to the source 6 a and target 6 b volumes, respectively, while thePiT copy relationship 14 is active.

FIG. 4 illustrates and embodiment of a copy map 24, which may comprise abitmap that includes a cell for each track in the target volume 6 b, ortarget location, including the target set of logical addresses. Thecells for the target tracks including the target set of target logicaladdress to receive source logical addresses are set to indicate copy,e.g., “1”. The cells representing tracks in the target volume 6 b thatare not part of the PiT copy relationship, i.e., excluding the targettracks including the target set, may have a value to indicate that theyare not to be copied, e.g., “0”. Other values and settings could be usedto indicate the tracks to copy and the tracks not to copy as part of thePiT copy relationship being established. Thus, each cell set to indicateto copy represents a plurality of target logical addresses involved inthe copy operation.

The cells, indicators, in the copy map 24 may each represent a targetgroup of target logical addresses, including target logical addresses ininvolved in the copy relationship tracks 14. The target groupsrepresented by the indicators, cells, in the copy map 14 may eachrepresent groupings of logical addresses other than tracks. In a furtherembodiment, the copy map 24 may indicate tracks in the source volume 6 ahaving the source set of logical addresses to copy.

FIGS. 3, 4, and 5 provide an embodiment of information included in thePiT copy establish command, the source and target relationshipinformation, and the copy map. This information described as included inthese data structures and commands is not considered to be limiting, andadditional and modified information may be included in differentembodiments. Further, the information described in FIGS. 3, 4, and 5 maybe separated into additional commands and data structures.

FIGS. 5 a and 5 b illustrate an embodiment of operations performed bythe copy manager 12 to process a PiT copy establish command 50 toestablish a PiT copy relationship 14, such as a FlashCopy establishcommand, e.g., FCESTABL. With respect to FIG. 5 a, the copy manager 12receives (at block 100) a PiT Copy Establish Command 50 indicating thefirst 54 and last 56 source logical addresses and the first 58 and last60 target logical addresses. The copy manager 12 determines (at block102) a first source track including the first source logical address 54and a first target track including the first target logical address 56to which the data is copied. The copy manager 12 would use a volume mapto determine the mapping of logical addresses to tracks in the storages4 a, 4 b. The copy manager 12 quiesces (at block 104) Input/Output (I/O)operations to the source set of logical addresses to copy. The copymanager 12 then generates (at block 106) source relationship information20 indicating the first source track 74, the first target track 76, andthe length 78 related to the logical block addresses to copy. The copymanager 12 further quiesces (at block 108) I/O operations to the targetset of logical addresses to be updated. The copy manager 12 generates(at block 110) target relationship information 24 indicating the firstsource logical address 74, the first target logical address 76, and anumber of logical addresses to copy 78. In the quiesce operations atblock 104 and 108, the copy manager 12 may quiesce I/O to only thedetermined source set and target set of logical addresses to copy or totracks including the source and target sets of logical addresses.Alternatively, the queisce of I/O may be to the entire volumes 6 a, 6 b.

The copy manager 12 generates (at block 112) a copy map 24 includingindicators, e.g., cells, wherein each indicator represents a pluralityof logical block addresses, such as a track. The copy manager 12determines (at block 114) copy indicators comprising indicators in thecopy map 24 representing the tracks including the target set of targetlogical addresses. With respect to FIG. 5 b, the copy manager 12determines (at block 120) whether only a portion of the first targettrack or the last target track, in the range of tracks including thetarget set, includes target logical addresses in the target set. If not,which means the source logical addresses to copy line up and fill eachtrack including the target set of logical addresses, then the copymanager 12 sets (at block 122) all the copy indicators to indicate thatthe source logical addresses mapping to the target tracks represented bythe copy indicators need to be copied.

If (from the yes branch of block 120) only a portion of the first orlast target track includes logical addresses in the target set, then thecopy manager 12 copies the data for those target tracks that onlypartially include target set logical addresses as part of establishingthe PiT copy relationship 14. The copy map 24 will not indicate to copythe first or last target tracks updated as part of the establishcommand. In this way writes to a portion of the target track that didnot include the logical addresses in the target set will not be copiedas part of the PiT relationship because they copy map 24 will notindicate that the target tracks partially including PiT data need to becopied. If (at block 126) only a portion of the first target trackincludes logical addresses in the target set, then the copy manager 12copies (at block 128) the source logical addresses that map to the firsttarget track to the first target track. If (at block 130) only a portionof the last target track includes logical addresses in the target set orif (from the no branch of block 126) the first target track does notonly partially store logical addresses of the target set, then the copymanager 12 copies (at block 132) the source logical address in thesource set that map to the last target track to the last target track.

After copying logical addresses for the first and/or last target track(from block 132 or the no branch of block 130), the copy manager 12 sets(at block 134) the copy indicators, except for the first target trackand/or the last target track that are updated, to indicate that thesource logical addresses for the target tracks represented by the copyindicators needs to be copied, e.g., to one. The copy indicators for thefirst and/or last target track that are updated at blocks 128 and/or 132are not set to indicate that the source tracks need to be copied. Aftergenerating the PiT relationship information and data structure (fromblock 122 or 130), such as the copy map 24 and after copying sourcelogical addresses in the source set that map to partial filled firstand/or last target tracks (from block 134), complete is returned (atblock 138) to the application or user that initiated the PiT copyestablish command 50.

In an alternative embodiment where the copy map 24 indicates sourcetracks having the source set of logical addresses, if the source set ofsource logical addresses maps to only a portion of a first source trackand/or a last source track including a portion of the source set oflogical addresses, then the first source track and/or the last sourcetrack only partially filled with PiT logical addresses are copied to atleast one of the corresponding target tracks as part of the PiTestablish relationship operation. In such case, the copy map 24 wouldnot indicate that the first and/or last source tracks need to be copied.Further, in this alternative embodiment, the returning of the completeto the virtual copy establish command is performed in response tocopying the first source track and/or the last source track to thecorresponding target tracks.

After the PiT copy relationship 14 is established, hosts (not shown) maysubmit writes to the controller 2 for source logical addresses in thesource volume 6 a including data in one of the established PiT copyrelationships 14. The writing of data to a source logical address in aPiT copy relationship 14 that has not been copied to the target volume 6b would trigger the copy manager 12 to perform a copy-on-write operationto copy data at the source logical addresses in the copy relationship 14to the target storage 6 b before they are updated so as to preserve thePiT relationship.

In certain described embodiments, upon receiving a write to a sourcelogical address in a copy relationship 14, the copy manager 12determines a target group of target logical addresses also in the copyrelationship, such as a target track, that include the source logicaladdress to update. The copy manager 12 determines the source logicaladdresses corresponding to the target logical addresses in the targetgroup, and copies the determined source logical addresses to thedetermined target group. In this way, the mapping of the source andtarget logical addresses in the relationship information 70 is used todetermine the source logical addresses in the copy relationship 14 thatneed to be copied to the target storage 6 b. This type of mapping isperformed because in certain described embodiments the source logicaladdresses in the source set are in source tracks that may be differentnumbered tracks than the target tracks including the target set oflogical addresses to be updated by the source logical addresses in thedestage group.

FIG. 6 illustrates an embodiment of operations performed by the copymanager 12 to process an update to a source logical address in a sourcevolume 6 a. If a write request is directed to multiple source logicaladdresses, then the operations of FIG. 6 may be performed for eachsource logical address in the write. Upon receiving (at block 200) theupdate, the copy manager 12 considers the source relationshipinformation 20 to determine (at block 202) whether the source logicaladdress to update is within the range of source logical addresses, asdefined by the first source logical address 74 and the number logicaladdresses 78 (FIG. 3), in one PiT copy relationship 14. If not, the copymanager 12 copies (at block 204) the update to the source volume 6 a. If(at block 202) the source logical address to update is in one PiT copyrelationship 14, then the copy manager 12 determines (at block 206) thetarget track including the target logical address in the target set tobe updated by the source logical address being updated. This may bedetermined from the target relationship information 22 by determiningthe target logical address corresponding to the source logical addressto update from the ranges of source logical addresses and target logicaladdresses as defined by the first source logical address 74, the secondtarget logical address 76 and the number logical addresses to copy 78.

The copy manager 12 then determines (at block 208) whether they copy map24 for the PiT copy relationship 14 being considered indicates that thedetermined target, e.g., target group, track was updated, i.e., whetherthe bit or indicator for the determined target track, or target group,indicates the target track was updated. The indicator may indicate thetrack was updated if it does not indicate the track needs to be updatedor if it has a value indicating the track is current. If (from the yesbranch of block 208) the determined target track to which the sourcelogical address to update is to be copied has been updated, then the PiTdata for the source logical address has already been copied to thedetermined target track (target group) and control proceeds to block 204to write the update to the source logical address in the source volume 6a.

If (at block 208) the copy map 24 indicates the determined target trackhas not been updated, then the copy manager 12 determines (at block 210)the target logical addresses in the determined target track having thetarget logical address to update. The copy manager 12 determines (atblock 212) the source logical addresses in the source set to be copiedto the target logical addresses in the at least one target track. Thedetermined source logical addresses are then copied (at block 214) tothe determined target logical addresses in the target track or targetgroup. The at least one copy indicator in the copy map 24 for theupdated target track is set (at block 216) to indicate that the at leastone target track was updated. After the target track is updated, controlproceeds to block 204 to apply the update to the source logical address.

With the described embodiments of FIG. 6, an update to source logicaladdresses is processed by determining the source track including thesource logical addresses that will be destaged together. The targettracks having the source logical addresses to be destaged together isthen determined, and then source logical addresses are copied tocorresponding target logical addresses in the copy relationship as partof performing a copy-on-write for the updated source track.

Once the copying of the source logical addresses to the at least onetarget track is confirmed, the source track having the source logicaladdress to update is destaged to the source track, so that thepoint-in-time data is destaged and not overwritten with newer data.

FIG. 7 illustrates an embodiment of operations performed by the copymanager 12 to copy source logical addresses to target logical addressesin the copy relationship as part of a background copy operation if theestablish command 50 indicates a background copy operation 62. Thebackground copy operation is performed to copy all the source logicaladdresses in the PiT copy relationship 14 to the target volume 6 b toprovide a redundant copy of the source logical addresses. Uponinitiating (at block 250) the background copy operation, the copymanager 12 selects (at block 252) one indicator, e.g., bit, in the copymap 24 representing target logical addresses, e.g., a track, that havenot been updated. The copy manager 12 may select a bit in the copy map24 that that is adjacent in the copy map 24 to the last selected bit toupdate sequential target tracks. in the target volume 6 b. The copymanager 12 determines (at block 254) source logical addresses from thesource set that are to be copied to the selected target logicaladdresses. This may be determined from the source relationshipinformation 20 from the source and target logical address ranges definedin the source relationship information 20, by determining the sourcelogical addresses in the source range that correspond to the selectedtarget logical addresses.

The determined source logical addresses are copied (at block 256) to theselected target track and then the selected indicator in the copy map 24is set (at block 258) to indicate that the target track has beenupdated.

The described embodiments provide techniques for allowing a PiT copyestablish operation to specify source and target logical addresses thatmap to source and target tracks having the specified source and targetlogical block addresses, respectively. In described embodiments, a firstand/or last of the source tracks including the source logical addressesmay only have a portion of the source logical addresses to copy and afirst and last of the target tracks including the target logicaladdresses may only have a portion of the target logical addresses. Insuch case, the source logical addresses that map to only a portion ofthe first and/or last target tracks are copied to the first and/or lasttarget tracks during the establish operation. Further, the copy mapindicating target tracks that need to be updated with source tracks doesnot indicate that data needs to be copied for the first and/or lasttarget tracks for which the source logical addresses are copied duringthe establish operation.

The described embodiments further provide techniques for handlingupdates to source logical addresses in a PiT copy relationship. Becausesource tracks are destaged in a destage group, such as a track,including the updated source logical address, the described embodimentsdetermine the target tracks having the target logical addresses in thePiT copy relationship that are updated by source logical addresses inthe source track being destaged. The source logical addresses are thencopied to the corresponding target logical addresses in the determinedat least one target track in the PiT copy relationship.

Described embodiments further provide techniques for performing abackground copy operation of source logical addresses in a PiT copyrelationship by determining a copy indicator representing a targettrack, determining the source logical addresses that map to the targetlogical addresses in the target track in the PiT copy relationship, andthen copying the determined source logical addresses to the targettrack. The described embodiments allow the managing of updates andbackground copy operations for source logical addresses in a PiT copyrelationship when source and target data are expressed as logicaladdresses and when different ranges of source and target logicaladdresses are specified.

The described operations may be implemented as a method, apparatus orcomputer program product using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. Accordingly, aspects of the embodiments may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,aspects of the embodiments may take the form of a computer programproduct embodied in one or more computer readable medium(s) havingcomputer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present invention are described above with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The terms “an embodiment”, “embodiment”, “embodiments”, “theembodiment”, “the embodiments”, “one or more embodiments”, “someembodiments”, and “one embodiment” mean “one or more (but not all)embodiments of the present invention(s)” unless expressly specifiedotherwise.

The terms “including”, “comprising”, “having” and variations thereofmean “including but not limited to”, unless expressly specifiedotherwise.

The enumerated listing of items does not imply that any or all of theitems are mutually exclusive, unless expressly specified otherwise.

The terms “a”, “an” and “the” mean “one or more”, unless expresslyspecified otherwise.

Devices that are in communication with each other need not be incontinuous communication with each other, unless expressly specifiedotherwise. In addition, devices that are in communication with eachother may communicate directly or indirectly through one or moreintermediaries.

A description of an embodiment with several components in communicationwith each other does not imply that all such components are required. Onthe contrary a variety of optional components are described toillustrate the wide variety of possible embodiments of the presentinvention.

Further, although process steps, method steps, algorithms or the likemay be described in a sequential order, such processes, methods andalgorithms may be configured to work in alternate orders. In otherwords, any sequence or order of steps that may be described does notnecessarily indicate a requirement that the steps be performed in thatorder. The steps of processes described herein may be performed in anyorder practical. Further, some steps may be performed simultaneously.

When a single device or article is described herein, it will be readilyapparent that more than one device/article (whether or not theycooperate) may be used in place of a single device/article. Similarly,where more than one device or article is described herein (whether ornot they cooperate), it will be readily apparent that a singledevice/article may be used in place of the more than one device orarticle or a different number of devices/articles may be used instead ofthe shown number of devices or programs. The functionality and/or thefeatures of a device may be alternatively embodied by one or more otherdevices which are not explicitly described as having suchfunctionality/features. Thus, other embodiments of the present inventionneed not include the device itself.

The illustrated operations of the figures show certain events occurringin a certain order. In alternative embodiments, certain operations maybe performed in a different order, modified or removed. Moreover, stepsmay be added to the above described logic and still conform to thedescribed embodiments. Further, operations described herein may occursequentially or certain operations may be processed in parallel. Yetfurther, operations may be performed by a single processing unit or bydistributed processing units.

The foregoing description of various embodiments of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Many modifications and variations are possible in lightof the above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. The above specification, examples and data provide acomplete description of the manufacture and use of the composition ofthe invention. Since many embodiments of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims herein after appended.

What is claimed is:
 1. A computer program product for copying datainvolving at least one storage, wherein the computer program productcomprising a non-transitory computer readable storage medium havingcomputer readable program code embodied therein that executes to causeoperations, the operations comprising: providing a copy relationshipindicating a source set of a subset of source logical addresses in theat least one storage to copy to a target set comprising a subset oftarget logical addresses in the at least one storage, wherein the sourcelogical addresses map to source tracks and wherein the target logicaladdresses map to target tracks; receiving an update to a source logicaladdress within the source set of logical addresses that has not beencopied to the corresponding target logical address as part of the copyrelationship; determining the target logical address corresponding tothe source logical address to be updated according to the copyrelationship; determining a target group of target logical addresses inthe target set that include the determined target logical address,wherein the target logical addresses in the target group are in thetarget set; determining the source logical addresses in the source setthat correspond to the target logical addresses in the target group; andcopying the determined source logical addresses to the target logicaladdresses in the determined target group.
 2. The computer programproduct of claim 1, wherein the target logical addresses in a targetstorage including the target set of target logical addresses arearranged in target groups, including the determined target group.
 3. Thecomputer program product of claim 1, wherein the target groups comprisetarget tracks configured in the target storage.
 4. The computer programproduct of claim 2, wherein the operations further comprise: maintaininga copy map including a plurality of indicators, including one indicatorfor each of the target groups, wherein at least one of the indicatorsrepresenting at least one of the target groups indicates that the targetlogical addresses in the represented at least one target group have notbeen updated since the copy relationship was established.
 5. Thecomputer program product of claim 4, wherein the determining of thetarget logical address corresponding to the source logical address toupdate and the determining of the target group including the determinedtarget logical address are performed in response to receiving the updateto the source logical address, wherein the operations further comprise:determining from the copy map whether the indicator for the determinedtarget group indicates that the target logical addresses in thedetermined target group have been updated with the corresponding sourcelogical addresses in the copy relationship, wherein the operation ofcopying the determined source logical addresses is performed in responseto determining that the indicator for the determined target groupindicates that target group has not been updated.
 6. The computerprogram product of claim 1, wherein the source tracks including thesource set are different numbered tracks than the target tracksincluding the target set of logical addresses.
 7. The computer programproduct of claim 1, wherein the operations further comprise: writing thereceived update to the source logical address in response to receivingacknowledgment that the determined source logical addresses in thesource set were copied to the determined target logical addresses in thedetermined target group.
 8. The computer program product of claim 1,wherein the logical addresses comprise logical block addresses (LBAs)and wherein the source tracks and the target tracks are in a same volumeor in different volumes in the at least one storage.
 9. A computerprogram product for copying data involving at least one storage, whereinthe computer program product comprising a non-transitory computerreadable storage medium having computer readable program code embodiedtherein that executes to cause operations, the operations comprising:providing a copy relationship indicating a source set of a subset ofsource logical addresses in the at least one storage to copy to a targetset comprising a subset of target logical addresses in the at least onestorage, wherein the source logical addresses map to source tracks andwherein the target logical addresses map to target tracks; initiating acopy operation to copy source logical addresses in the source set totarget logical addresses in the target set; selecting target logicaladdresses in the target set that have not been updated in response toinitiating the copy operation; determining source logical addresses fromthe source set that are to be copied to the selected target logicaladdresses; and copying the determined source logical addresses to theselected target logical addresses.
 10. The computer program product ofclaim 9, wherein the operations further comprise: providing a copy mapincluding a plurality of indicators, wherein each of the indicatorsrepresents a plurality of the target logical addresses, wherein at leastone of the indicators representing target logical addresses in thetarget set indicates that the represented target logical addresses havenot been updated since the copy relationship was established; selectingone indicator indicating that the represented target logical addresseshave not been updated, wherein the selected target logical addressescomprise the target logical addresses represented by the selectedindicator; and setting the selected indicator to indicate that therepresented target logical addresses have been updated in response tothe copying.
 11. The computer program product of claim 9, wherein eachindicator represents a track, wherein the indicators representing targetlogical addresses in the target set that have not been updated indicatethat all the target logical addresses in the represented track comprisetarget logical addresses in the target set that have not been updated.12. A system for copying data involving at least one storage,comprising: a processor; and a computer readable storage medium havingcomputer program code executed by the processor to perform operations,the operations comprising: providing a copy relationship indicating asource set of a subset of source logical addresses in the at least onestorage to copy to a target set comprising a subset of target logicaladdresses in the at least one storage, wherein the source logicaladdresses map to source tracks and wherein the target logical addressesmap to target tracks; receiving an update to a source logical addresswithin the source set of logical addresses that has not been copied tothe corresponding target logical address as part of the copyrelationship; determining the target logical address corresponding tothe source logical address to be updated according to the copyrelationship determining a target group of target logical addresses inthe target set that include the determined target logical address,wherein the target logical addresses in the target group are in thetarget set; determining the source logical addresses in the source setthat correspond to the target logical addresses in the target group; andcopying the determined source logical addresses to the target logicaladdresses in the determined target group.
 13. The system of claim 12,wherein the target groups comprise target tracks configured in thetarget storage.
 14. The system of claim 13, wherein the operationsfurther comprise: maintaining a copy map including a plurality ofindicators, including one indicator for each of the target groups,wherein at least one of the indicators representing at least one of thetarget groups indicates that the target logical addresses in therepresented at least one target group have not been updated since thecopy relationship was established.
 15. The system of claim 14, whereinthe determining of the target logical address corresponding to thesource logical address to update and the determining of the target groupincluding the determined target logical address are performed inresponse to receiving the update to the source logical address, whereinthe operations further comprise: determining from the copy map whetherthe indicator for the determined target group indicates that the targetlogical addresses in the determined target group have been updated withthe corresponding source logical addresses in the copy relationship,wherein the operation of copying the determined source logical addressesis performed in response to determining that the indicator for thedetermined target group indicates that target group has not beenupdated.
 16. The system of claim 12, wherein the source tracks includingthe source set are different numbered tracks than the target tracksincluding the target set of logical addresses.
 17. A system for copyingdata involving at least one storage, comprising: a processor; and acomputer readable storage medium having computer program code executedby the processor to perform operations, the operations comprising:providing a copy relationship indicating a source set of a subset ofsource logical addresses in the at least one storage to copy to a targetset comprising a subset of target logical addresses in the at least onestorage, wherein the source logical addresses map to source tracks andwherein the target logical addresses map to target tracks; initiating acopy operation to copy source logical addresses in the source set totarget logical addresses in the target set; selecting target logicaladdresses in the target set that have not been updated in response toinitiating the copy operation; determining source logical addresses fromthe source set that are to be copied to the selected target logicaladdresses; and copying the determined source logical addresses to theselected target logical addresses.
 18. The system of claim 17, whereineach indicator represents a track, wherein the indicators representingtarget logical addresses in the target set that have not been updatedindicate that all the target logical addresses in the represented trackcomprise target logical addresses in the target set that have not beenupdated.
 19. A method for copying data involving at least one storage,comprising: providing a copy relationship indicating a source set of asubset of source logical addresses in the at least one storage to copyto a target set comprising a subset of target logical addresses in theat least one storage, wherein the source logical addresses map to sourcetracks and wherein the target logical addresses map to target tracks;receiving an update to a source logical address within the source set oflogical addresses that has not been copied to the corresponding targetlogical address as part of the copy relationship; determining the targetlogical address corresponding to the source logical address to beupdated according to the copy relationship determining a target group oftarget logical addresses in the target set that include the determinedtarget logical address, wherein the target logical addresses in thetarget group are in the target set; determining the source logicaladdresses in the source set that correspond to the target logicaladdresses in the target group; and copying the determined source logicaladdresses to the target logical addresses in the determined targetgroup.
 20. The method of claim 19, wherein the target groups comprisetarget tracks configured in the target storage.
 21. The method of claim20, wherein the operations further comprise: maintaining a copy mapincluding a plurality of indicators, including one indicator for each ofthe target groups, wherein at least one of the indicators representingat least one of the target groups indicates that the target logicaladdresses in the represented at least one target group have not beenupdated since the copy relationship was established.
 22. The method ofclaim 21, wherein the determining of the target logical addresscorresponding to the source logical address to update and thedetermining of the target group including the determined target logicaladdress are performed in response to receiving the update to the sourcelogical address, wherein the operations further comprise: determiningfrom the copy map whether the indicator for the determined target groupindicates that the target logical addresses in the determined targetgroup have been updated with the corresponding source logical addressesin the copy relationship, wherein the operation of copying thedetermined source logical addresses is performed in response todetermining that the indicator for the determined target group indicatesthat target group has not been updated.
 23. The method of claim 19,wherein the source tracks including the source set are differentnumbered tracks than the target tracks including the target set oflogical addresses.
 24. A method for copying data involving at least onestorage, comprising: providing a copy relationship indicating a sourceset of a subset of source logical addresses in the at least one storageto copy to a target set comprising a subset of target logical addressesin the at least one storage, wherein the source logical addresses map tosource tracks and wherein the target logical addresses map to targettracks; initiating a copy operation to copy source logical addresses inthe source set to target logical addresses in the target set; selectingtarget logical addresses in the target set that have not been updated inresponse to initiating the copy operation; determining source logicaladdresses from the source set that are to be copied to the selectedtarget logical addresses; and copying the determined source logicaladdresses to the selected target logical addresses.
 25. The method ofclaim 24, wherein each indicator represents a track, wherein theindicators representing target logical addresses in the target set thathave not been updated indicate that all the target logical addresses inthe represented track comprise target logical addresses in the targetset that have not been updated.